FBI Director James B. Comey testifies during for a House Intelligence Committee hearing in Longworth Building on Russian interference with the 2016 election in March. (Tom Williams/CQ Roll Call File Photo)

Former FBI Director James B. Comey is a central figure in the investigations into scandals surrounding the 2016 presidential campaign and the Trump administration, a role that has heightened since he was abruptly fired in May.

His unusual choice to announce, just a week and a half before Election Day, that the FBI had reopened its investigation into Hillary Clinton’s private email server is widely believed to have impacted the course of the election.

His departure raised questions about the future of the FBI investigation into connections between the Russian government and members of Trump’s inner circle. His testimony Thursday, front of the Senate Intelligence Committee, will be the first time he has spoken publicly since then.

Here’s a look back at how it came to this:

March 2, 2015

The New York Times reports that Hillary Clinton used a personal email account while she was Secretary of State, a violation of State Department policies and a potential security risk.

April 12, 2015

Clinton announces she is running for president.

July 23, 2015

The inspector general for the intelligence community alerts Congressional oversight committees that classified material had been found on Hillary Clinton’s home email server that she had used as Secretary of State. The FBI opens a criminal investigation.

Late April, 2016

Officials at the Democratic National Committee learn that Russian hackers have invaded their computer system.

July 5, 2016

Comey delivers a blistering critique of Clinton at a press conference, saying her handling of classified material was, “extremely careless,” and hackers may have compromised her emails. But he concludes that he is recommending against charging Clinton in the case.

July 7, 2016

Comey testifies before Congress about the Clinton investigation, repeating his criticism and discussing his decision to close the case. He repeats his assertion that the case is closed.

July 27, 2016

Trump, at a press conference, says he hopes the Russian government has hacked Clinton’s emails and implores it to publish what it found. The comment fuels questions about the Russian government meddling in the campaign.

July, 2016

The FBI opens an investigation into members of the Trump campaigns’ contacts with the Russian government.

September, 2016

October, 2016

FBI investigators seize Weiner’s computer. Weiner was married at the time to Clinton confidante and campaign aide Huma Abedin. Agents discover that thousands of Abedin’s emails had been backed up on Weiner’s computers, including some that had apparently moved through Cinton’s server.

October, 2016

Comey learns of the Clinton emails on Weiner’s server. He determines that he is obligated to tell Congress he is reopening the investigation. He does so in a letter on Oct. 28.

November 6, 2016

Days before the election, Comey sends a letter to Congress saying that the new emails did not contain any new information.

November 8, 2016

Trump is elected president.

March 20, 2017

Comey acknowledges for the first time during testimony before the House Intelligence Committee that the FBI is investigating connections between members of the Trump administration and the Russian government.

May 3, 2017

Comey testifies before Congress that Abedin regularly sent emails to Weiner so he could print them out, and that she had sent, “hundreds of thousands of emails,” to Weiner, “some of which contain classified information.”

May 8, 2017

ProPublica reports that Comey exaggerated the number of emails that Abedin sent to Weiner.

May 9, 2017

The Washington Post and the Associated Press report that none of the emails were designated as classified when they were sent.

May 9, 2017

May 9, 2017

Trump announces that Comey has been dismissed. The White House claims that Comey was fired because of Justice Department concerns about his job performance.

May 10, 2017

President Trump discussed his decision to fire Comey with Russian Diplomats during an Oval office meeting, according to The New York Times. "I just fired the head of the FBI," Trump says. "He was crazy, a real nut job. I faced great pressure because of Russia. That’s taken off."

May 11, 2017

Trump contradicts his aides' explanations for Comey's firing during an interview with NBC news. Trump says that he thinks Comey is, "a showboat," and "a grandstander," and that the FBI investigation was on his mind when he made the decision.

May 16, 2017

A memo emerges stating that President Trump asked Comey to back off from the Flynn investigation. Comey wrote the memo shortly after a meeting with Trump at the Oval office in February. House Oversight Committee Chairman Jason Chaffetz, R-Utah, demands that the FBI turn over all “memoranda, notes, summaries and recordings” of discussions between Trump and Comey.

May 17, 2017

The Justice Department announces that it has appointed former FBI director Robert Meuller, a widely respected figure in the intelligence community, as special council overseeing the Russia investigation.

May 19, 2017

Comey agrees to testify before the Senate Intelligence Committee.

June 5, 2017

White House officials say in a statement that President Trump will not invoke executive privilege to prevent Comey from testifying, ending days of speculation that Comey would not be allowed to speak.

June 6, 2017

The New York Times reports that, the day after President Trump asked Comey to end the FBI's Flynn investigation, Comey asked Attorney General Jeff Sessions to ensure that he was never left alone with the president. Comey reportedly did not mention Trump's request regarding the Flynn investigation to Sessions, an omission that is likely to come up when he is questioned by the Senate Thursday.